For example, regarding belts used for power transmission in infinite variable speed drives, a laminated ring formed by stacking a plurality of metal rings is used to combine a plurality of elements arranged in a laminated construction like a ring. The metal rings constituting such a laminated ring are formed by cutting a cylindrical drum, which has been formed by performing weldbonding on both ends of a rectangular thin metallic plate, in round slices with a predetermined width.
Conventionally the following method is known: when the cylindrical drum is cut with a predetermined width to form the metal rings, one end of the drum is supported by clamping, a rotating grindstone is pressed from the outside of the other end of the drum, and the grindstone is moved in the circumferential direction of the drum, so that the drum is cut. However, when the drum is cut using the grindstone, a grinding allowance corresponding to the width of the grindstone is necessary, thereby reducing the yields of metal rings obtained from one drum. Further, when the drum is cut using the grindstone, drainage becomes complicated due to the grinding of a worn grindstone.
Thus, for example, a method of cutting the drum is known which uses a shearing cutter instead of the grindstone. In this case, although blurs do not appear on the corner edge of the inner periphery of the metal ring, relatively large blurs appear on the corner edge of the outer periphery, so that it takes a long time to perform shaping using barrel polishing after cutting. Further, another method is known in which a drum is cut by pressing shearing cutters to both of the inner periphery and the outer periphery of the drum, so that blurs are prevented on the corner edges of the inner periphery and the outer periphery. However, the shearing cutters may be damaged because the cutters may come into contact with each other after cutting the drum.
In order to eliminate such inconvenience, it is an object of the present invention to provide a cutter for a thin metallic plate, by which time for shaping cut edges and the like is reduced, manufacturing efficiency is improved, a thin metallic plate is cut with a predetermined width with enhanced yields, and the life of a cutter is increased.